Evidence of silicic acid leakage to the tropical Atlantic via Antarctic Intermediate Water during Marine Isotope Stage 4

Type Article
Date 2013-06
Language English
Author(s) Griffiths James D.1, Barker Stephen1, Hendry Katharine R.2, Thornalley David J. R.1, Van De Flierdt Tina3, Hall Ian R.1, Anderson Robert F.4
Affiliation(s) 1 : Cardiff Univ, Sch Earth & Ocean Sci, Cardiff CF10 3AT, S Glam, Wales.
2 : Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA.
3 : Univ London Imperial Coll Sci Technol & Med, Dept Earth Sci & Engn, London, England.
4 : Lamont Doherty Earth Observ, Palisades, NY USA.
Source Paleoceanography (0883-8305) (Amer Geophysical Union), 2013-06 , Vol. 28 , N. 2 , P. 307-318
DOI 10.1002/palo.20030
WOS© Times Cited 14
Keyword(s) silica leakage, diatom, carbon dioxide, SAMW, AAIW
Abstract Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW) are the main conduits for the supply of dissolved silicon (silicic acid) from the deep Southern Ocean (SO) to the low-latitude surface ocean and therefore have an important control on low-latitude diatom productivity. Enhanced supply of silicic acid by AAIW (and SAMW) during glacial periods may have enabled tropical diatoms to outcompete carbonate-producing phytoplankton, decreasing the relative export of inorganic to organic carbon to the deep ocean and lowering atmospheric pCO(2). This mechanism is known as the silicic acid leakage hypothesis (SALH). Here we present records of neodymium and silicon isotopes from the western tropical Atlantic that provide the first direct evidence of increased silicic acid leakage from the Southern Ocean to the tropical Atlantic within AAIW during glacial Marine Isotope Stage 4 (similar to 60-70ka). This leakage was approximately coeval with enhanced diatom export in the NW Atlantic and across the eastern equatorial Atlantic and provides support for the SALH as a contributor to CO2 drawdown during full glacial development.
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Griffiths James D., Barker Stephen, Hendry Katharine R., Thornalley David J. R., Van De Flierdt Tina, Hall Ian R., Anderson Robert F. (2013). Evidence of silicic acid leakage to the tropical Atlantic via Antarctic Intermediate Water during Marine Isotope Stage 4. Paleoceanography, 28(2), 307-318. Publisher's official version : https://doi.org/10.1002/palo.20030 , Open Access version : https://archimer.ifremer.fr/doc/00264/37526/